Digital telecommunications exchange system

Abstract

A telecommunications system operable to connect terminal devices for exchange of data has control devices (ST, GST), an accessory control device (HS), and a memory (SP). The control devices effect addressed connections via hierarchical coupling fields (KF) to which terminal devices (T, PC, VP) and/or transmission lines (VL) are coupled, each by two user channels and one signalling channel. Routine transmissions to and from a telephone apparatus (T), computer (PC) or the like are effected by connection addressing codes transmitted on the signalling channel. For special functions or transmissions, a unique code is inserted in the signalling data, which causes the control device (GST, ST) to pass the signalling data to the accessory control device (HS). The accessory control device replaces the unique code with a connection addressing code if the terminal is authorized, and returns the signalling information to the control device, where it effects the desired connection. The memory (SP) stores data not used in switching, such as "telephone book" listings, usage data, authorizations and the like. When a transmission involves a change in redundantly stored data in the memory and in the terminal device memories, the control devices and/or terminal devices locate and update all occurrences of the data. The system connects special functions to the exchange, without interfering with basic switching functions.

We claim: 
     
       1. A digital telecommunications exchange system with a control device having a memory, and with a large number of termination circuits for making operative connections via subscribers' lines including at least one of connection lines for terminal devices and line circuits for additional exchange systems, the subscribers' lines in each case having at least two user channels and one data/signalling channel, information on the user channels being transmitted between the connection lines and a coupling device of the telecommunications exchange system, and information on the data/signalling channel being carried between said subscribers' lines and the control device via a bus system, the telecommunications exchange system comprising: a data memory;   at lest one computer coupled to one of the connection lines, the computer having a computer memory; and,   an accessory control device associated with said control device, and means to transmit data between the computer and the control device, for effecting data transmission in at least one direction between the computer and the data memory, and wherein changes in contents of said data memory are monitored by the accessory control device, the accessory control device including a table of information as to correspondence between data in the data memory and at least one of data int he computer memory and other data in the data memory, whereby changes to the data memory are likewise effected in corresponding contents of at least one of the data memory and the computer memory.   
     
     
       2. The digital telecommunications exchange system of claim 1, wherein said computer while active is arranged to regularly send a report of its operating state to the accessory control device for recording. 
     
     
       3. The digital telecommunications exchange system of claim 1, wherein the table of the accessory control device is updated to contain information identifying data in the memory associated with the control device which has been changed, and identifying data as to the particular computer initiating the change. 
     
     
       4. The digital telecommunications exchange system of claim 3, further comprising means for amending data in at least one additional said computer identified in the table of the accessory control device as having data corresponding to the data which has been changed. 
     
     
       5. The digital telecommunications exchange system of claim 1, wherein exchange of data between the computer and the control device takes place via the data/signalling channel. 
     
     
       6. The digital telecommunications exchange system of claim 1, comprising at least two computers on the exchange system, the computers being operable to exchange data under control of the accessory control device, formation of a connection between said computers taking place on the basis of information from the accessory control device and transmission of the data taking place via at least one of the user channels. 
     
     
       7. The digital telecommunications exchange system of claim 1, comprising a plurality of computers connected to the exchange system and wherein access by the computers to the memory of the control device is controlled by the accessory control device. 
     
     
       8. The digital telecommunications exchange system of claim 1, wherein changes in the data in the memory of the control device are also possible by additional terminal devices connected to the telecommunications exchange system and authorized to make said changes. 
     
     
       9. The digital telecommunications exchange system of claim 1, wherein the accessory control device forms a part of the control device. 
     
     
       10. The digital telecommunications exchange system of claim 1, wherein a plurality of accessory control devices are provided which are activated by items of information on at least one of the data channel and the signalling channel. 
     
     
       11. The digital telecommunications exchange system of claim 1, wherein the table in the accessory control device contains information on active computers on the exchange system. 
     
     
       12. The digital telecommunications exchange system of claim 1, wherein data matching takes place between the accessory control device and one of a plurality of computers on the exchange system, and wherein corresponding data matching is accomplished with others of the computers by data transmission occurs via at least one of the user channels. 
     
     
       13. The digital telecommunications exchange system of claim 1, wherein functions of the accessory control devices are stored in a certain active computer. 
     
     
       14. The digital telecommunications exchange system of claim 13, wherein in that in the event of an outage of said active computer, said functions are assumed by one of the accessory control device and another active computer. 
     
     
       15. A digital telecommunications exchange system with a control device having a memory, the telecommunications exchange system having a large number of connection circuits for making operative connections between at least two of a plurality of terminal devices including one of terminals and exchange systems, via communication lines in each case having at least two user channels and one data/signalling channel, information on the user channels being transmitted over connection lines between the terminal devices and a coupling device of the telecommunications exchange system, and information on the data/signalling channel being carried between the terminal devices and the control device via a bus system, for effecting addressed connections of the communication lines between the terminal devices, comprising: an accessory control device associated with the control device, and wherein switching information intended for the control device and transmitted via the data/signalling channel is marked by a first indication code by one of said terminals and exchange devices, said information being processed in the control device of the telecommunications exchange system, and instead of the first indication code, a different special indication code being used by at least one of said terminals and exchange devices, respectively, which are authorized, and transmitted to the accessory control device, the accessory control device being operable to replace said different special indication code with the first indication code, whereupon the switching information is transmitted to the control device of the telecommunications exchange system for effecting a desired function.   
     
     
       16. The digital telecommunications exchange system of claim 15, wherein the first indication code includes information for effecting a connection between terminal devices on the exchange system and the different special indication code authorizes a change in memory data initiated by one of the terminal devices. 
     
     
       17. The digital telecommunications exchange system of claim 16, wherein said change in memory is communicated in turn to additional ones of the terminal devices identified by a able in memory including addresses of the additional terminal devices where data corresponding to the changed memory data is stored. 
     
     
       18. The digital telecommunications exchange system of claim 15, wherein the first indication code is interpreted by the control device for effecting a connection between terminal devices, and for an authorized transmission the different special indication code is interpreted by the control device of passing a transmission to the accessory control device, the accessory control device inserting the first indication code in place of the different special indication code if the terminal is authorized, and returning the transmission to the control device, whereupon a connection for the authorized transmission is effected. 
     
     
       19. The digital telecommunications exchange system of claim 18, wherein the authorized transmission operates a special function appended to the telecommunications system, said special function being initiated, authorized and effected using connections of the exchange system otherwise employed for routine transmission of data between terminal devices.